1. Field of the Invention
The present invention relates to an improved magnetic disk drive unit having a magnetic head provided accessibly to a recording region of a rotating magnetic disk, and particularly to a magnetic head slider, a magnetic head assembly, and a magnetic disk drive unit, each of which includes a magneto-resistance effect element for readout.
2. Description of the Related Art
In recent years, along with a tendency toward smaller sizes and larger capacities of magnetic disk drive units used for external storages of computers, flying heights of head sliders have come to be reduced, and it has been required to realize contact recording/reproducing performed with a slider being separated from a recording medium by a significantly small flying height or being in contact with a recording medium. On the other hand, related art magnetic induction heads have an inconvenience that as a peripheral velocity of the head (velocity of the head relative to that of a medium) is reduced depending on reductions in sizes of magnetic disks as media, a reproducing output of the head is degraded. To cope with such an inconvenience, it has been required to develop a composite head slider having an electromagnetic transducer which includes a magneto-resistance effect element (MR element) capable of obtaining a large reproducing output not depending on a peripheral velocity, more specifically, even at a low peripheral velocity in combination with a coil for writing data.
In composite head sliders, at the time of writing data, a current modulated in response to data is made to flow in a coil, to thereby magnetically record information on a magnetic disk as a medium. At the time of reading out information recorded on a medium, a constant sensing current is supplied to an MR element, to convert a change in magnitude of a signal magnetic field leaked from a recording track of the medium into a change in resistance, whereby information recorded on the medium is reproduced as a change in voltage value.
A composite head slider has an electromagnetic transducer including an MR element generally formed on a slider body by a thin film process or the like and a coil for writing data, and is mounted on a leading end portion of a suspension made from a stainless steel by adhesive bonding or the like.
Lead wires for connecting an MR element and a coil to a recording/reproducing circuit of a magnetic disk drive unit are formed by copper patterns printed on a suspension. By mounting the suspension to a leading end portion of an actuator arm, the MR element and coil are connected to the recording/reproducing circuit via a flexible printed circuit board (FPC) or the like.
In related art composite head sliders, a pair of terminals connected to an MR element are in an electrically opened state. Accordingly, when an operator charged with static electricity handles such a composite head slider having an MR element or carries the composite head slider in a state that the slider is housed in a case made from a synthetic resin or the like liable to charged, an overcurrent due to electrostatic charge flows in the MR element, thereby causing a problem associated with burning of the MR element or the like.
A related art magnetic head slider including a composite head slider mounted on a suspension causes the same problem as that described above. That is to say, in the related art magnetic head assembly, a pair of lead wires (or wiring patterns), which are formed on a suspension in such a manner that one-ends thereof are connected to an MR element, are in an electrically opened state.
Accordingly, when an operator charged with static electricity handles such a magnetic head assembly, an overcurrent due to electrostatic charge flows in the MR element, tending to cause burning of the MR element.
Accordingly, an object of the present invention is to provide a magnetic head slider capable of preventing the occurrence of burning of an MR element due to static electricity.
Another object of the present invention is to provide a magnetic head assembly capable of preventing the occurrence of burning of an MR element due to static electricity.
A further object of the present invention is to provide a magnetic disk drive unit easily assembled by using a magnetic head provided by such a magnetic head slider or magnetic head assembly.
The other objects of the present invention will be apparent from the following description.
According to a first aspect of the present invention, there is provided a magnetic head slider including a slider body having an air bearing surface opposed to a magnetic disk, an MR element provided on the slider body, and first and second terminals connected to the MR element. This magnetic head slider is characterized by a switching element for short-circuiting the first and second terminals in response-to an external input.
With this configuration, since the switching element for short-circuiting the first and second terminals in response to an external input is adopted, at the time of carrying the magnetic head slider or assembling a magnetic head assembly or a magnetic disk drive unit using the magnetic head slider, the flow of an overcurrent due to electrostatic charge or the like in the MR element can be prevented by short-circuiting the first and second terminals by the switching element, and at the time of operating the magnetic head slider, a sensing current is made to flow in the MR element by releasing the short-circuit between the first and second terminals in response to the external input. With this first aspect of the present invention, it is possible to provide the magnetic head slider capable of preventing the occurrence of damages of the MR element due to static electricity.
Preferably, the switching element includes a photo-transistor provided on the slider body in such a manner as to connect the first and second terminals to each other. In this case, light incident on the photo-transistor can be used as the external input. Accordingly, when a magnetic disk drive unit is assembled such that the magnetic head slider is enclosed in an opaque disk enclosure, the short-circuit between the first and second terminals and the release thereof by the switching element can be automatically performed. In this way, the magnetic disk drive unit can be easily produced.
According to a second aspect of the present invention, there is provided a magnetic head assembly including a slider body having an air bearing surface opposed to a magnetic disk, an MR element provided on the slider body, and a suspension on which the slider body is mounted and which has first and second wiring patterns connected to the MR element. This magnetic head assembly is characterized by a switching element for short-circuiting the first and second wiring patterns in response to an external input.
With this configuration, like the first aspect of the present invention, it is possible to provide the magnetic head assembly capable of preventing the occurrence of damages of the MR element due to static electricity.
Preferably, the switching element includes a photo-transistor which is provided on the suspension in such a manner as to connect the first and second wiring patterns to each other. In this case, light incident on the photo-transistor can be used as the external input. Accordingly, like the above described case, a magnetic disk drive unit can be easily produced.
According to a third aspect of the present invention, there is provided a magnetic head slider characterized by a switching element for turning on/off connection between at least one of first and second terminals and an MR element in response to an external input.
For example, at the time of carrying the magnetic head slider or assembling a magnetic head assembly or a magnetic disk drive unit using the magnetic head slider, the above connection is turned off by the switching element, and at the time of operating the magnetic head slider, the above connection is turned on by the switching element. As a result, it is possible to provide the magnetic head slider capable of preventing the occurrence of damages of the MR element due to static electricity.
Preferably, the magnetic head slider further includes a third terminal for receiving an external input, and the switching element includes a transistor connected to the third terminal on the slider body. This magnetic head slider is convenient because at the time of carrying the magnetic head slider or the like, any external energy is not required to turn off the above connection by using the switching element. At the time of operating the MR element, since the magnetic head assembly or the-magnetic disk drive, unit having the magnetic head slider has been already assembled, an electrical signal can be easily supplied as an external input to the switching element via the third terminal.
Preferably, to perform discharge between the first and second terminals at all times, a resistance having a resistance value larger than a resistance value of the MR element is connected between the first and second terminals. The reason why the resistance value of the resistance is larger than that of the MR element is to make a large amount of a sensing current flow in the MR element for operating the MR element, thereby enhancing a sensitivity of sensing. Accordingly, the resistance having a resistance value being as large as ten times the resistance value of the MR element is preferably provided between the first and second terminals.
According to a fourth aspect of the present invention, to obtain the same effect as that obtained by the third aspect of the present invention, there is provided a magnetic head assembly characterized by a switching element for turning on/off connection between at least one of first and second wiring patterns and an MR element in response to an external input.
According to a fifth aspect of the present invention, there is provided a magnetic disk drive unit including a disk enclosure, a magnetic disk provided rotatably in the disk enclosure, and a magnetic head provided accessibly to a recording region of the magnetic disk. The magnetic head is configured as the magnetic head slider of the present invention or the magnetic head assembly of the present invention.
With this configuration, since the occurrence of damages, due to static electricity, of the MR element in the magnetic head slider or magnetic head assembly is prevented in accordance with the present invention, it is possible to easily produce a magnetic disk drive unit.
The above and other objects, features and advantages of the present invention and the manner of realizing them will become more apparent, and the invention itself will best be understood from a study of the following description and appended claims with reference to the attached drawings showing some preferred embodiments of the invention.